..my 92 Dakota V8 was selected 2 times in a row for "test only" smog ll shake down. It passed both times and came back cleaner the 2nd time due to a fresh oil change and new air filter. But I got hit 2wice back to back. Even the test tech eas surprised to see me back. It's supposed to be random..but?? 68.00 bucks just for the test plus reg.fee. If I could go to my local gas station for a test it would have cost 29.00 for the test. Even wit 96k miles on it it's neary as clean as a 2006 said the smog tech. Slightly more noX everything else was way under the limit. Elevated nox may hve been the egr valve port. It has a new egr valve in it so the port my be dirty.